Although the HED-loss function proved to be useful in training for edge detection.
Training time can be reduced and edges further penalized by maximizing intersection-over-union [1]}.
Then, we consider the objective function,
\(\mathcal {L}_{\mathit {iou}} = 1 - \frac{P \cap Y}{P \cup Y} = 1 - \frac{\sum _{v \in Y} P_v Y_v}{\sum _{v \in Y} P_v + Y_v - P_v Y_v}.\) 
